fix(python): correct BarometerData field types to scalars

[Bartok9]

Summary

• Align BarometerData Python defaults with C++ BarometerBase::Output / RpcLibAdaptorsBase::BarometerData (altitude/pressure/qnh as real scalars, not Quaternionr/Vector3r).
• Offline unittest documents the scalar contract without requiring a live sim.

Motivation

Python client types.py historically declared wrong barometer field shapes. That mismatches the RPC adaptor and confuses typed clients/nested from_msgpack defaults. C++ SoT:

struct Output {
  TTimePoint time_stamp;
  real_T altitude; // meters
  real_T pressure; // Pascal
  real_T qnh;
};

Verification

• PYTHONPATH=PythonClient python3 -m unittest tests.test_barometer_data_types -v → 2 passed
• Did not change flight/arm/geofence paths
• Orthogonal to open utils.py PRs (fix(python): use np.frombuffer in string_to_*_array helpers #9795/fix(python): harden write_file empty payloads and PFM handles #9796)

Notes

• AI-assisted implementation; human-reviewed before push
• Typo freeze observed (real type bug, not docs casing)

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